One way for you to get the Invention Constructor on your home is take the science job and when you go to work to the science lot, go to build mode and build a room and put a Invention Constructor in the room then save the room to your library. When you get back home go to build mode and place the room you saved onto your lot and you should then have it at home.
Or you can go to the community gallery and search for science room. There are some there you can download and place on your home lot.